Process for preparing n-substituted lactams

ABSTRACT

A process for the preparation of N-substituted lactams of the formula   WHEREIN A is a substituted or unsubstituted aliphatic hydrocarbon chain having 3 to 11 carbon atoms, said substituents comprising one or more alkyl groups each having 1 to 4 carbon atoms; and R is hydrogen or a hydrocarbon radical having 1 to 17 carbon atoms, comprising reacting at least one starting lactam of the formula   WITH AN ORGANIC HALOGEN COMPOUND OF THE FORMULA X - CH2-R wherein X is chlorine, bromine or iodine, in the presence of an alkali metal hydroxide in solid form or in at least 50% aqueous solution at a reaction temperature of from 20*C to 120*C.

United States Patent n91 Liissi et al.

r451 Feb, 11, 1975 PROCESS FOR PREPARING N-SUBSTITUTED LACTAMS [75] Inventors: Heinz Liissi; Clau Berther, both of 7' Chur/Gr; Josef Studinka, Zurich, all

of Switzerland [73] Assignee: lnventa AG fur Forschung und Patentverwertung, Zurich, Switzerland [22] Filed: July 25, 1973 [21] Appl. No.: 382,461

[30] Foreign Application Priority Data OTHER PUBLICATIONS Tafel et al., Chem. Ber., Vol. 40, (1907).

Primary ExaminerHenry R. .liles Assistant ExaminerRobert T. Bond Attorney, Agent, or FirmBierman & Bierman [57] ABSTRACT A process for the preparation of N-substituted lactams of the formula wherein A is a. substituted or unsubstituted aliphatic hydrocarbon chain having 3 to l l carbon atoms, said substituents comprising one or more alkyl groups each having 1 to 4 carbon atoms; and R is hydrogen or a hydrocarbon radical having I to 17 carbon atoms, comprising reacting at least one starting lactam of the formula I with an organic halogen compound of the formula X CH -R wherein X is chlorine, bromine or iodine, in the presence of an alkali metal hydroxide in solid form or in at least- 50% aqueous solution at a reaction temperature of from 20C to 120C.

15 Claims, N0 Drawings PROCESS FOR PREPARING N-SUBSTITUTED LACTAMS arty, .l. org. Chem. 29, 2748 (1964). The alkali lactal mates required for the purpose were prepared in advance in each case by reacting the alkali metals or the alkali metal hydrides with the corresponding lactams in the presence of an inert solvent. In consequence of reduction by the nascent hydrogen formed and in consequence of condensation under the influence of the strongly basic medium, however, by-products which impair the purity and the yield of the N-alkyllactam subsequently produced are formed. (A. Ciaperoni, L.

Mariani and G. B. Gechele, Chim. Ind. (Milan) 50, 772 25 1968)). Moreover, this method is uneconomic in consequence of the use of the costly alkali metals or alkali metal hydrides.

An appreciable advance compared with this conventional laboratory method is. found in the paper by G. L. lsele and A. Lilttringhaus (Synthesis 1971, 266). The authors describe the alkylation of caprolactam with nbutyl bromide, benzyl chloride or octadecyl chloride in Nll the presence ofdimethyl sulfoxide as solvent and potassium hydroxide as hydrogen halide acceptor. The authors attribute their results to a specific action of the dimethyl sulfoxide employed by them as solvent, namely to a marked promotion of the formation of the potassium salts of the amides used. In spite of its advantages when compared with older methods, this process is not really suitable for commercial use on a large scale. The yields (which amount to 70 to 83%), the use of relatively costly potassium hydroxide, and the simultaneous use of large amounts of a somewhat exotic solvent are detrimental to its economy.

Surprisingly, it has now been found that lactams, even in the absence of solvents, can be alkylated with high yields using primary alkyl or aralkyl halides and with alkali metal hydroxides as hydrogen halide acceptors.

The lactams which can be used according to the present invention are compounds of the following general formula:

Pyrrolidone, piperidone, 7-t.butyl caprolactam, the

commercial isomer mixture of B,B,8-and B,6,8-trimethylcaprolactam, oenantholactaim, capryllactam, caprinlactam, laurinlactam and in particular caprolactam.

5 The alkylating agents which can be employed according to the present invention are compounds of the following general formula:

X CH R X is chlorine, bromine or iodine and is preferably chlorine. R is hydrogen or a hydrocarbon radical with l to 17 carbon atoms. This hydrocarbon radical may consist of straight or branched aliphatic chains or of alicyclic or aromatic rings. It may contain all these elements in any combination and, moreover, olefinic double bonds. 5 Examples of such organic halogen compounds are:

Methyl chloride, ethylchloride, n-butyl bromide, octadecyl iodide, allyl chloride, methallyl chloride, bromomethylcyclohexane, benzyl chloride, 2-chloromethylnaphthalene and 3-(p-methylphenyl- )propyl bromide. Preferably, R--CH2 is a methyl,

ethyl, allyl or benzyl group.

Suitable as bases splitting off hydrogen halide, according to the present invention, are in particular the hydroxides of the alkali metals. For economic reasons, sodium hydroxide is generally preferred. Remarkably, in fact, this cheap base is also suitable for performing the simple process according to the invention in by far the majority of cases, whereas lsele and Li'ittringhaus (loc.cit.) were only able to use potassium hydroxide for their more expensive method.

The reaction forming the basis of the process according to the invention proceeds in accordance with the following equation:

c 0 Ak X' A, X, R having the significances previously mentioned 40 and Ak standing for an alkali metal cation.

is carried out, however, complete conversion is not always achieved. In practice, it often proves to be an advantage if the conversion of at least one constituent is as complete as possible. This can be achieved by using one or even two of the constituents in excess. One mo] of the lactam is preferably reacted with 0.5 to 5 mols of the organic halogen compound and with 0.5 to 2 mols of the alkali metal hydroxide.

In the preferred method of carrying out the present process of the invention, the lactam and the organic halogen compound are first put in the reaction vessel and heated. The alkali metal hydroxide is added at such rate that, when the reaction temperature is reached, the heat of reaction which is released can be removed. The reverse procedure, that is, putting the base in first 0 together with the lactam and then adding the alkylating agent often has an unfavorable effect on the yields.

The alkali hydroxide may readily be used in solid form. It is dissolved without difficulty during the reaction with precipitation of the corresponding alkali halide. Out of purely practical considerations, however, it will frequently be preferred to add. the base in the form of an aqueous solution. With this method, however, it must be taken into consideration that as the amount of water added increases both the reaction velocities and the yields obtained decrease. For these reasons, a solution of the base which is diluted more than 50% is not advisable. With the more advantageous use of more concentrated solutions of alkali hydroxide, for example 73% sodium hydroxide, heated supply vessels and feed piping should be provided in order to prevent the base from crystallizing out.

The reaction temperatures which can be employed lie within the range of 20 to 120C. At higher temperatures, secondary reactions make themselves increasingly noticeable. At temperatures which are too low, the alkylation becomes slow. In many cases, a temperature between 50 and 80C has proved to be very satisfactory. The optimum reaction temperature in a particular case depends, however, essentially on the nature of the starting products, and in particular the nature of the alkylating agent. In this connection, there apply the generally known rules, according to which the alkyl iodides and, to a lesser extent, the alkyl bromides, are more reactive than the corresponding alkyl chlorides, and according to which halogen compounds with an ally] and benzyl structure are more reactive than those which have no double bond systems or have double bond systems further removed from the halogen atom.

The alkylating reactions carried out according to the present invention are distinctly exothermic, so that the steps known generally to the expert must be taken to control the reaction temperature and to remove the heat of reaction.

The carrying out of the reaction under pressure is advantageous whenalkylation is performed with an alkyl halide which is gaseous under normal conditions, such as, for example, methyl chloride. In such cases, the reaction is appreciably accelerated by the use of pressure, the conversion levels and yields are increased, and the reaction time can be shortened accordingly.

Simultaneous use of an inert solvent during the reaction is not necessary and tends to slow down the reaction due to the dilution of the constituents and to increase the cost of recovering the end product. Never theless, the addition of an inert liquid of suitable boiling point, such as, for instance, hexane, has proved to be advantageous in some cases because the heat of reaction can be carried off and the water of reaction separated by the boiling liquid. At the same time, not only is it unnecessary for this liquid tobe miscible with the reaction mixture, but it is even an advantage for it to be immiscible or only limitedly miscible therewith. For the reasons first mentioned, it is desirable to limit addition of inert liquid to what is absolutely necessary. lf necessary, the alkylating agent itself may also take over the function of the inert liquid if its boiling point is in conformity with the desired reaction temperature at the pressure prevailing.

The process according to the invention may also be used for converting lactam mixtures. This fact may be utilized to cause the reaction also of those lactams, such as, for instance, laurinlactam, whose melting points are far above the optimum reaction temperature. In such cases, a lower-melting mixture of this high-melting lactam with a second lactam is used with advantage. During the recovery, the two N-substituted lactams obtained can then be separated by known methods, as for example by distillation.

In another method for converting high-melting lactams, the N-substituted lactam formed in the reaction is added to the starting lactam prior to the reaction in an amount such that a sufficient lowering of the melting point occurs.

In the final reacted mixture there is found unreacted starting products, inert liquid if added, the N- substituted lactam formed, the water added together with the base and the water formed during the reaction, and alkali halide which is precipitated for the most part. They can be separated in very simple manner by distillation after the alkali halide has been filtered off. Preferably, any free alkali hydroxide which may possibly still be present is neutralized beforehand with acid.

The N-substituted lactams prepared in accordance with the invention are valuable solvents, plasticizers and lubricants. Some of them can be polymerized to give valuable plastics (see, for example, Makromol. Chemie 80, pp. 44 et seq. (l964) and Swiss Patent Specification 5l0,7l8).

The following Examples are intended to illustrate the present invention without, however, limiting it in any way.

EXAMPLE 1 1130 g of caprolactam (l0 mols) are melted at C and saturated with gaseous methyl chloride while stirring vigorously. While passing methyl chloride through without interruption, a 50% sodium hydroxide solution is allowed to drip in and at the same time the reaction vessel is cooled with water at a temperature of 50C. The rate at which the sodium hydroxide solution drips in is so chosen that the reaction temperature drops to 60C after 10 minutes. At the same time, common salt begins to precipitate in finely divided form. From this point on, the rate at which the sodium hydroxide is added is so chosen that in spite of the cooling with water at a temperature of 50C a temperature of 60C is maintained in the vessel. After 20 minutes, 160 g of 50% sodium hydroxide (2 mols) have been added, 320v g (8 mols) of beads of pure sodium hydroxide are then added portionwise. All the sodium hydroxide has been added within H 1 hours and 6 mols of methyl chloride have been absorbed. The mixture is allowed to finish reacting for another 6 hours at 60C. As before, as much methyl chloride as the mixture will absorb is constantly added. Since, with time, the heat of reaction is no longer sufficient to maintain the desired temperature, the external temperature of the reaction vessel must be suitably increased. At the end of the reaction, about 9 mols of methyl chloride have been absorbed and further absorption takes place only extremely slowly.

The liquid and colorless reaction product contains fine crystals of sodium chloride which are filtered with suction and washed three times with 300 ml of benzene in each case. The benzene extracts are evaporated and the residue is combined with the first filtrate to form the product mixture.

Water and the remaining benzene are then driven off from the product mixture at normal pressure and a sump temperature of up to 150C. Subsequent vacuum distillation at 2 mm Hg yields 1060.6 g. ofa liquid fraction passing over between C and l l8C and which consists chiefly of N-methylcaprolactam and still contains considerable amounts of unconverted caprolactam. g of caprolactam are recovered as the last fraction.

No. Composition Weight 1 N-Methylcaprolactam, 99% 856.7 g 2 {78.2% N-Methylcaprolactam 21.8% caprolactam 50.2 g 3 Caprolactam 145.0 g

The precipitated common salt is filtered off from the mixture and washed with methanol. The separately collected methanol washing liquor is neutralized with 68 ml of concentrated hydrochloric acid to pH 7 and then extracted with benzene. The evaporation residue of the benzene extract is distilled together with the main part of the filtered mixture at 0.1 mm Hg. The fraction passing over at 94 to 1 12C (894 g) is rectified once more in a l-meter Vigreux column. 122 g of un- Finally, therefore, from 1130 g of caprolactam used, 10 converted lactam pass over between 1 12C and 150C 895.9 g of N-methylcaprolactam are obtained and 266 g of caprolactam are recovered.

(0.1 mm Hg). The rectification yields the (Gas chromatography Boiling point n,,20 Amount trimethylcaprolactam caprolactam 6468C/0.l mm Hg 1.4713 19.7 g 89.0 68-72C/0.1 mm Hg 1.4733 21.6 g 95.3 7273C/0.l mm Hg 1.4741 278.7 g 99.7 73-74C/0.1 mm Hg 1.4743 367.1 g 100.0 74-75C/0.l mm Hg 1.4750 81.8 g 97.5 2.5 Residue m.p.= 104.5 g

76.5% of the caprolactam used was converted. The

In all, at the end of the reaction there are still 228 g yield of N methylcaprolactam is 92.1% based on the of unconverted trimethylcaprolactam, so that the concaprolactam consumed. version is 77.5% based on lactam used. 763 g of N-methylcaprolactam b.p 86 88C (0.8 mm Hg) N-methyltrimethylcaprolactam are formed. From this n,,20 1.4839 there is calculated a yield of 90% of the theoretical It is also possible to operate in exactly the same way based on converted trimethylcaprolactam. There is at a reaction temperature of 80C. 1n this case, 73% of 645.8 g of N-methyltrimethylcaprolactam with a purity the caprolactam is converted and the N- of 99.7% or more. The residual N-methyllactam can methylcaprolactam is obtained in a yield of 92.6% likewise be isolated in pure form from the first and last based on the caprolactam consumed. fractions by further separating operations, for example In otherwise exact analogy to the Example which has by rectification operations. been described, all the sodium hydroxide may also be EXAMPLE 3 added in the form of a a or a solution or in solid form. The results obtained in this way are 400 g (3.54 Of caprolactam and 400 g summarized hereunder: mols) of laurinlactam are melted at 90C and allowed Sodium hydroxide concentration) 50% 60% 70% 100% Caprolactam conversion 62.1% 63.8% 71.1% 76.4% Yield of N-methyl caprolactam (based on caprolactam 67.0% 84.1% 90.0% 91.7% consumed) Percent by weight These results show clearly that both the conversion to cool down to C while methyl chloride is introof caprolactam and the yield of N-methylcaprolactam duced with vigorous stirring. The addition of sodium fall with increasing dilution of the sodium hydroxide hydroxide in pellet form is then commenced. Immedisolution. I 50 ately thereafter the reaction vessel is cooled with 50 to Piperidone, n a am and capry tam an be 55C water so that the temperature in the reaction mixconverted in similar manner with methyl chloride. ture is kept at 70 to 74C. Within 50 minutes, 222 g (5.56 mols) of solid sodium hydroxide are added in EXAMPLE 2 portions. The reaction is allowed to continue for an- 1,000 g (6.45 mols) of the isomer mixture of 3,13,8- 55 other hour at 72C, whereupon another 80.8 g (2.02 and B,6,fi-trimethylcaprolactam are melted at 83C and mols) of solid sodium hydroxide are added. At the saturated with methyl chloride while stirring vigorsame time, the temperature of the water bath is inously. During the whole of the rest of the test the stircreased to C, as a result of which the temperature ring is maintained and a little more methyl chloride in the reaction vessel increases to the same level within than is absorbed is constantly passed through. Within 60 45 minutes. A quarter of an hour after the last addition half an hour, 258 g (6.45 mols) of sodium hydroxide of sodium hydroxide, a second portion of 400 g (2.02 beads are added in portions. At the same time, with the mols) of laurinlactam is added. About 20 minutes later, commencement of the addition, the reaction vessel is the temperature of the mixture reaches 88C, wherecooled with water at a temperature of 50C, so that the upon a third amount of 160 g of sodium hydroxide (4 temperature of the mixture falls to 70C within 15 min- 65 mols) is added in portions. Finally, the mixture is alutes. After the addition of the alkali has been com pleted, the mixture is allowed to finish reacting for about another 8 hours at the same temperature. In all, 142.5 liters of methyl chloride are absorbed.

lowed to finish reacting for another minutes at 90C and for 4% hours at 9394C. Throughout the reaction, the mixture is vigorously stirred and an amount of methyl chloride is passed through such that After cooling the precipitated sodium chloride and crystallized laurinlactam are filtered off from the mix- EXAMPLE 4 sumed, are formed. The main amounts of these two substances are present in Fractions 12 and 22 with a purity of 98.5%. Of course, further amounts of the N- methyllactams can be isolated by further dividing up of the remaining fractions in the manner hereinbefore described.

ff i s fi f g g z d extracm" 80 g 2 mols) of sodium hydroxide are added within e f f l half an hour while stirring vigorously in 4portions of 20 ove e s g o prac y pure aurm ac am g each to a mixture of 226 g (2 mols) of caprolactam,

are recovered 295 g (2.4 mols) of n-propyl bromide and 100 ml of After evaporation of the petroleum ether, the filtrate o is S m u into three fractions b distillation, hexane boiling at 70 C. After a short time, the boiling p p point rises to 75C, whereupon another 50 ml of hex- Amount -P- ane are added. On further heating under reflux, the

I 45668 mm Hg boiling point of the mixture rises again to 80C after 2 173.5 g 100-112:C/0.2 mm Hg about 5 hours and another 30 ml of hexane are added. 3 323'0 5 427163 C/0'3 mm Hg The total reaction time is 7 hours. In this time, 30 ml f of water of reaction is separated in a separator ars ,lmpure laurmlactam le t as resldue' By ranged below the reflux condenser and expelled with recrystallization from ethyl acetate, 124 g of pure lacthe hexane vapor. tam is recovered therefrom. A further portion of laurmlactam (48.2 g) is separated from Fraction 3 by filtra-- l i d afte uwashing i h petroleum h The precipitated sodium bromide is filtered off and F i 1 i ifi d i a Vi column washed with hexane. After evaporation of the hexane, and split up into the three Fractions l 1, 12 and 13 and' the filtrate is distilled under vacuum. The main amount a residue R 1. Fractions 2 and 3 are separated together (258.5 g) of the Product Passes Over at to 102C in a similar column into Fractions 21, 22 and 23; 62.1 and 0.8 mm Hg. Between 102 and 115C and 0.8 mm g of laurinlactam being recovered as residue. The I-Ig there follows 14.3 g of the last fraction which still amounts and boiling points of these fractions and the contains 65.8% of N-n-propylcaprolactam in addition compositions thereof determined by gas chromatograto 30.5% of caprolactam. In the subsequent rectificaphy are given in Table 1. tion of the main amount in a l-meter Vigreux column,

Table 1 Fraction 11 12 13 R l 21 22 23 N0.

Amount 17.4 g 390.5 g 11.5 g 40.3 g 20.4 g 291.1 g 62.9 g

Boiling 711-2"(/().3 mm 72-3(/0.2 mm 73142C/0.1 mm m 85-150170 mm 1512(/0.3 mni 153-160"- poiut (70.3 mm H I H v H Hg n,,20 1.41125 1.4831 1.4848 1.4975 1.4830 1.4972 1.4976

methylcaprolactam 94.4% 98.5% 47.5% 47.5% 0.2% Capro- 2.9% 01% 0.9% lactam N-methy- 2.6% 1.3% 49.4% 89.2% 51.2% 98.6% 89.5% llaurinlactam Laurin- 0.1% 0.2% 0.2% 10.7% 0.1% 1.2% 10.2% lactam lmpur- 2.9% 0.3% 0.3% ities Summing up, it is apparent therefrom that the 400 g the following fractions are obtained: of caprolactam used are converted almost completely and that 384 g of the 800 g of laurinlactam (or 48%) is are used up. 401 g of laurinlactam of good quality are recovered which can be used again in another charge. 0 Basically, another 15 g can be isolated from Fractions P Boiling point Amount lactam lactam R 1, 22 and 23 by further separation operations. In all, 416 g of N-methylcaprolactam, i.e. 92.5% of the theog g-z gzag: mm 5 g $3 3 2 retical yield, and 401 of N-methyllaurinlactam, i.e. mnrnm {gig 21.8; 59:5 35:3 98% of the theoretical yield based on laurinlactam con- Residue 16.0 g 2.1 97.5

In all, 216.6 g of N-n-propylcaprolactam are formed and 39 g of caprolactam are not converted. The yield is 85%.based on the converted caprolactam and based on the caprolactam used.

EXAMPLE 60 g (1.5 mols) of sodium hydroxide in pellet form are added in portions within 20 minutes while stirring pass over at 120 to 136C and 0.4 mm Hg. g of unconverted trimethylcaprolactam are recovered as the last fraction. The rectification of the main distillate in a l-meter Vigreux column yields the following fracvigorously to a mixture of 170 g (1.5 mols) of caprolac- 5 tions:

Gas chromatography tam, 137 g (1.8 mols) of allyl chloride and 80 ml of hexane boiling at 54C. Thereafter, further heating is carried out under reflux. After a reaction time of 7 hours, the temperature of the boiling mixture has risen to 80C and 26 ml of water collects in a separator arranged below the reflux condenser and is driven off with the hexane vapor. Finally, hexane and excess allyl chloride are distilled off from the mixture, the sump temperature being increased to 150C.

In all, 71 g of the lactam are not converted and 278 g of N-allyltrimethylcaprolactam are formed. The lactam conversion is consequently 77% and the yield of N-allyllactam is 92.5% of the theoretical based on lactam consumed.

By further rectification, a 99.9% N-allyltrimethylcaprolactam (n,, 1.4803) can be obtained and shows the following analytical values. found: C 73.88%; H 10.52%; N 7.35%

Precipitated sodium chloride is filtered out of the recalculated: c 73.79%; H 10.84%; N 7.17% action product and is washed with methanol. After the methanol has been distilled off, the reaction product is EXAMPLE 7 rectified in a l-meter Vigreux column at 0.5 mm Hg. To 226 g (2 mols) of caprolactam and 304 g (2.4 Almost all the product passes over between 875 and 30 mols) of benzyl chloride is added an amount ofhexane 88.5"C and has a refractive index of 1.4924 to 1.4928. such that the mixture boils at 74C. While stirring vig- Three fractions are separated and exhibit the following orously, 80 g (2 mols) of sodium hydroxide pellets are physical properties and purity values: added within 6 minutes at this temperature, whereupon Gas chromatography Boiling point n,,20 Amount Allylcapro- Caprolactam lactam 87.5-88.0C/0.5 mm H 1.4924 155.9 g 97.8 1.9 88.0-88.5C/0.5 mm H 1.4928 29.0 g 96.0 4.0 88.5-99.5C/0.5 mm H 1.4932 14.3 g 88.9 11.1

Thus, 193.5 g of N-allylcaprolactam are formed and the heat of reaction liberated causes the hexane present g of Caprolactam are not Converted- The y to boil violently. Thereafter, heating is carried out for based Converted prolactam, is 875% of theoleti- 8 hours under reflux with continued stirring. Since, during this process the boiling point of the mixture falls, part of the hexane used is distilled off so that the temperature never falls below C. When the reaction EXAMPLE 6 is completed, 29 ml of water which. has been driven off g (2 mols) of solid sodium hydroxide i b d i with the hexane vapor has collected in a separator aradded portionwise, within one hour while stirring vigorranged below the reflux condenser. ously, to a mixture of 310 g (2 mols) of the isomer mix- 50 The residual hexane is distilled off from the mixture, ture of [3,3,5- and [3,8,6-trimethylcaprolactam, 183 g the sump temperature being increased to 140C. In (2.4 mols) of allyl chloride and ml of hexane boil- Order to prevent the product solidifying during the ing at 57C. Thereafter, heating is carried out for an adcooling, dilution with 300 ml of benzene is carried out. ditional 8 hours under reflux, 14 ml of water being The precipitated sodium chloride is thereafter filtered driven off with the hexane and allyl chloride vapors and 55 out and washed with benzene. After the wash benzene removed by way of a separator. 6V2 hours after the addition of the alkali has been completed, the boiling temperature of the mixture has risen to 74.5C, whereupon it is lowered to 72C by adding another 25 m1 of hexane.

has been distilled off, the residue is fractionated under vacuum. After a liquid first fraction, two solid fractions pass over and these have the following properties and the following compositions determined by gas chromatography:

B.p. M.p Amount N-benzyl- Caprocaprolactam lactam l20-l37C/0.l mm Hg about 40C 124.3 g 73.0 10.9 l34-l63C/0.1 mm Hg 53-55C 265.1 g 86.9

The precipitated common salt is filtered out and washed with benzene. The residue obtained after the wash benzene has been distilled off is combined with the filtered mixture and the whole is distilled under vacuum. 336.5 g of crude N-allyltrimethylcaprolactam The yield of N-benzylcaprolactam calculated from the analytical data is 79% of the theoretical yield based on the lactam used. After being :recrystallized three times from petroleum ether, the product of the second fraction is pure and melts at 56.5-- 575C.

EXAMPLE 8 To 170 g (2 mols) of pyrrolidone and 303 g (2.4 mols) of benzyl chloride there is added an amount of hexane such that the mixture boils at 70C; 80 g (2 mols) of sodium hydroxide in pellet form are added in portions within a quarter of an hour. Heating is carried out for 4 hours under reflux while stirring vigorously. 33 ml of water are separated from the evaporating hexane in a connected separator.

Finally, the hexane used is distilled off directly from the reaction'mixture, the sump temperature being increased to 152C. Thereafter, the precipitated sodium chloride is filtered out and washed with benzene. After the wash benzene has been distilled off, the filtered drocarbon radical having 1 to 17 carbon atoms, comprising reacting at least one starting lactam of the forwith an organic halogen compound of the formula X CH R wherein X is chlorine, bromine or iodine, in the presence of an alkali metal hydroxide, in solid form or in aqueous solution containing at least 50% of said hydroxide, at a reaction temperature of from 20C to 2. A process according to claim 1 wherein R is hydromixture is rectified in a l-meter Vigreux column at 0.6 15 gen, straight chain alkyl having 1 to 17 carbon atoms,

Consequently, 288 g of N-benzylpyrrolidone are 3. A process according to claim 1 wherein one mol formed in all. This is 82.5% of theoretical based on pyrof said starting lactam is reacted with 0.5 to 5 mols of rolidone used.

EXAMPLE 9 To a mixture of 113 g (1 mol) of caprolactam and 280.4 g of commercial, approx. 90%, octadecyl bromide (about 0.8 mol) there is added an amount of hexane such that the mixture boils at 75C. After adding 40 g (I mol) of sodium hydroxide beads, the mixture is boiled under reflux for 7 hours while stirring vigorously. In the process, the boiling temperature falls slowly to 70C. in all, 12 ml of water are expelled with the hexane vapors and removed by a separator.

The precipitated sodium bromide is filtered out and washed with benzene. The filtered solution of the mixture in 400 ml of benzene so obtained is extracted five times with 250 ml of water in each case. By concentration and distillation of the combined aqueous extracts, 21 g of unconverted caprolactam are recovered. After evaporation of the organic phase, 291 g of crude, waxlike N-octadecylcaprolactam are obtained (yield: 100% based on octadecyl bromide used, 98.5% based on caprolactam consumed). On the distillation of this product under 0.5 mm Hg, a main fraction of 226 g passes over at 231 to 235C. The purified N- octadecylcaprolactam obtained in this way is slightly yellow in color and melts at 355 37.5C. Yield: 77.5% based on octadecyl bromide used, 76.5%, based on caprolactam consumed.

What is claimed is:

l. A process for the preparation of N-substituted lactams of the formula said halogen compound and with 0.5 to 2 mols of said alkali metal hydroxide.

4. A process according to claim 1 carried out in the absence of solvent.

5. A process according to claim 1 wherein there is present 0.1 to 1.0 parts by weight of an organic liquid per part by weight of said starting lactam, said organic liquid taken from the class consisting of aliphatic, cycloaliphatic and aromatic hydrocarbons and aliphatic 'and cycloaliphatic ethers and being immiscible with water and boiling between 20 and 120C.

6. A process according to claim 1 wherein said alkali metal hydroxide is sodium hydroxide.

7. A process according to claim 5 wherein said organic liquid boils at said reaction temperature.

8. A process according to claim 1 wherein said alkali metal hydroxide is added to a previously prepared mixture comprising said starting lactam and said halogen compound.

9. A process according to claim 1 wherein said halogen compound is gaseous.

10. A process according to claim 1 wherein said halogen compound is allyl chloride, benzyl chloride, methyl chloride or ethyl chloride.

11. A process according to claim 9 wherein said reaction is carried out under such pressure that said halogen compound just boils out of the reaction mixture at said reaction temperature.

12. A process according to claim 1 wherein said starting lactam is caprolactam.

13. A process according to claim 1 wherein said reaction temperature is from 50 to C.

14. A process according to claim 1 wherein one said starting lactam, having a melting point above said reaction temperature, is combined with a lower melting starting lactam to form a starting lactam, mixture melting at or below said reaction temperature, whereby a plurality of said N-substituted lactams are formed.

15. A process according to claim 14 wherein said plurality of said N-substituted lactams are separated by distillation. 

1. A PROCESS FOR THE PREPARATION OF N-SUBSTITUTED LACTAMS OF THE FORMULA
 2. A process according to claim 1 wherein R is hydrogen, straight chain alkyl having 1 to 17 carbon atoms, or aralkyl.
 3. A process according to claim 1 wherein one mol of said starting lactam is reacted with 0.5 to 5 mols of said halogen compound and with 0.5 to 2 mols of said alkali metal hydroxide.
 4. A process according to claim 1 carried out in the absence of solvent.
 5. A process according to claim 1 wherein there is present 0.1 to 1.0 parts by weight of an organic liquid per part by weight of said starting lactam, said organic liquid taken from the class consisting of aliphatic, cycloaliphatic and aromatic hydrocarbons and aliphatic and cycloaliphatic ethers and being immiscible with water and boiling between 20* and 120*C.
 6. A process according to claim 1 wherein said alkali metal hydroxide is sodium hydroxide.
 7. A process according to claim 5 wherein said organic liquid boils at said reaction temperature.
 8. A process according to claim 1 wherein said alkali metal hydroxide is added to a previously prepared mixture comprising said starting lactam and said halogen compound.
 9. A process according to claim 1 wherein said halogen compound is gaseous.
 10. A process according to claim 1 wherein said halogen compound is allyl chloride, benzyl chloride, methyl chloride or ethyl chloride.
 11. A process according to claim 9 wherein said reaction is carried out under such pressure that said halogen compound just boils out of the reaction mixture at said reaction temperature.
 12. A PROCESS ACCORDING TO CLAIM 1 WHEREIN SAID STARTING LACTAM IN CAPROLACTAM.
 13. A process according to claim 1 wherein said reaction temperature is from 50* to 80*C.
 14. A process according to claim 1 wherein one said starting lactam, having a melting point above said reaction temperature, is combined with a lower melting starting lactam to form a starting lactam, mixture melting at or below said reaction temperature, whereby a plurality of said N-substituted lactams are formed.
 15. A process according to claim 14 wherein said plurality of said N-substituted lactams are separated by distillation. 